Re-usable hoisting insert for concrete slab



May 12, 1959 o. LIEBERTI 2,886,370

RE-USABLE HOISTING, INSERT FOR CONCRETE SLAB Filed March 18 1958 INVENTOR. OSCAR H. L/EBERT ATTORNEYS United States Patent 2,886,370 Patented May-12,'"'195Q RE-USABLE HOISTING INSERT FOR CON CRETE SLAB Oscar H. Liebert, Sunnyvale, Calif. Application March 18, 1958, Serial No. 722,346 2 Claims. (Cl. 29489) The present invention relates to a hoisting insert for a concrete slab, and pertains more particularly to such an insert which is readily removable after .use.

In the past, various types of inserts have been provided for molding into concrete slabs for use in hoisting the slabs into position. Some of such prior inserts have had portions thereof adapted for connecting to a hoisting means, which portions were capable of being removed after the slab had been erected, but in no known instance was the entire insert removable from the slab.

The present invention contemplates the provision of a strong, simple hoisting insert which can be molded integrally into a concrete slab while the latter is being poured, the insert being removable by a single blow on a projecting portion thereof so that the insert can be recovered for subsequent reuse, leaving a hole in the slab which can be filled with grout and smoothed off so as to leave the slab with no surface projections, exposed metal, or deformations.

A further object of the invention is to provide an improved and simplified knock-out hoisting insert for molding into a concrete slab.

A further object of the invention is to provide a knockout insert for molding into a concrete slab, the insert being formed to have strong engagement with the slab and with steel reinforcing elements therein for maximum "strength during a hoisting operation, but which can be easily removed by a blow on the projecting portion of the insert.

These, and other objects of the invention, will be apparent from the following description and the accompanying drawings, wherein:

Fig. l is a perspective view of a molded concrete slab having inserts embodying the invention molded therein and rigged to a hoisting means for erecting the slab.

Fig. 2 is an enlarged, fragmentary, sectional view taken along line 2--2 of Fig. 1, a fragment of a molding surface being shown.

Fig. 3 is a side elevational view of the insert shown in Figs. 1 and 2.

Fig. 4 is a perspective view of the insert shown in Figs. 1-3.

Fig. 5 is a fragmentary, sectional view generally similar to Fig. 2, but on a reduced scale, showing the insert in the process of being knocked free from a slab after the insert has served its purpose.

Briefly, the invention is illustrated as being embodied in a metal insert A for molding into a concrete slab B during the casting or pouring of such slab. Theinsert A comprises a body portion tapered inwardly toward a projecting upper end portion 11, the latter having a hole 12 therethrough. Laterally projecting hooked portions 13 and 14 are provided, one on each side of the insert, for supporting and engaging reinforcing rods 15 which are embedded in the slab B during the pouring of the latter. A transversely extending base portion 17 also is provided when required for supporting the insert in upright condition during the pouring of the slab. All

2 embedded side and edge surfaces of the insert are formed with suflicient draft to permit the insert A to be driven through and clear of the slab B in the direction of the arrow 18 in Fig. 5 by a blow on the exposed upper end 19 of the insert A as illustrated in Fig. 5. 1

Referring to the drawings in detail, the illustrative embodiment A of the invention may be either cast or other wise fabricated from suitable material, such as, for example, bronze or steel. The body portion 10 is platelike, and its sides 20 and 21 and lateral edges 22 and 23 are tapered inwardly from their lower toward their upper ends to provide suflicient draft to free the body A for downward removal from a slab B into which it has been cast, after the insert has served its purpose.

The body portion 10 is of sufficient height so that when the insert A is mounted upright upon a flat surface C (Figs. 1 and 2) upon which a concrete slab B is'to be cast, the upper portion 11 of the body portion 10 will project sufiiciently above the slab B when the latter is cast as to expose the hole 12 provided in the exposed upper end portion 11. The hole 12 preferably is of a diameter to receive a conventional rigging hook 24. The entire projecting upper portion 11 is of a size to pass I freely through a hole 27 (Fig. 5) left by the removal of the insert when it is driven out of the slab as shown in Fig. 5.

The laterally extending portions 13 and 14 are co-extensive with the lower end of the body portion 10. The upper edges 25 of these side extensions 13 and 14 may be substantially horizontal at 25a adjacent to the body portion 10, but slope upwardly at 25b adjacent their outer ends so as to provide hooked support for the rods 15 which are positioned to rest thereon during the pouring of a slab B.

The transversely extending support or base legs 17 are formed integrally with body portion 10, and medially of the lower end thereof. These support legs 17 project transversely from the body portion 10 a suflicient distance to provide a stable support for the insert A when the latter is mounted upright on a flat supporting surface C upon which a slab B is to be cast. All laterally directed surfaces of these transversely extending support legs 17 converge toward their upper ends, as do all of the other laterally directed, embedded portions of the insert A, to provide sufficient draft to permit its removal from a slab B into which it is cast as shown in Fig. 5.

In using the device, the insert A is placed upright, as shown in Fig. 3, on a suitable supporting surface C (Figs. 1 and 2) and the usual reinforcing steel, not shown except for the rods 15, is placed in a usual rectangular, open-top-box type of form, not shown, in which such slabs are conventionally cast. The two rods 15 then are placed one on each of the laterally extending, hookedtop base extensions 13 and 14.

The slab B is then cast in conventional manner to the form shown in Figs. 1, 2 and 5, and is allowed to harden, after which each insert A will be securely embedded therein, as shown in Figs. 1 and 2. The inserts may then be engaged by suitable hoisting means, such as the rigging D (Fig. l) and the slab A tilted or hoisted to its upright condition and secured in place in a usual and well known manner. After the slab has been permanently secured in place, the rigging hooks 24 are removed from the inserts A, which have thus served their purpose and are no longer needed. The inserts A may then be removed from the slab B by driving each of them through the slab, as shown in Fig. 5, by a sharp blow from a suitable implement such as a hammer E. The hole 27 left by the removal of the insert may then be filled in with rout, not shown, and smoothed off flush with the surfaces of the slab B. The inserts A thus removed may be used over and over indefinitely The invention provides a simple, inexpensive, rugged slab hoisting insert, which may be easily embedded in a concrete slab structure while the latter is being poured. .The insert is adapted to have interlocking engagement with steel reinforcing elements embedded in the slab structure to provide great strength and holding power, but may be easily removed in its entirety by a single hammer blow after the insert has performed its hoisting function. The hole from which the insert has been removed is easily filled with grout, which thereupon may be struck ofi flush with the slab side surfaces, leaving no metal either exposed on or adjacent to these surfaces of the slab with the possibility of rusting, collecting water, or discoloring.

While I have illustrated and described a preferred embodiment of the present invention, it will be understood, however, that various changes and modifications may be made in the details thereof without departing from the scope of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire to protect by Letters Patent is defined in the following claims.

I claim:

1. A knock-out hoisting insert for embedding in a rodreinforced concrete tilt-up wall slab during the molding of the latter upon a flat, horizontal molding base; said insert comprising a body portion of a height greater than the thickness of such slab so that when molded therein the upper part of said body portion will project above the upper surface of such slab, said body portion having a hole therethrough in its projecting upper portion, the bottom of said body portion being flat and substantially pependicular to its height, and of a width sufiicient to support the body in upright condition on such molding base, a pair of integral, reinforcing rod support portions extending laterally in opposite directions from the lower end of said body portion, the bottom of each rod support portion being flat and co-extensive with the bottom of said body portion, the top of each rod support portion being at a suflicient height, and so formed, as to support thereon a reinforcing rod for embedding the latter within a wall slab when the latter is poured on such molding base to embed said insert therein, all laterally directed surfaces of the body portion and of said laterally extending rod support portions converging inwardly toward their tops when the support is standing upright on its bottom, thereby to provide draft to permit downward removal, and to prevent upward withdrawal, of the insert through the slab, whereby, when the insert is mounted upright on such supporting base with a pair of reinforcing rods supported one on each rod support portion, and a wall slab is poured on said supporting base to embed the rods and all but the projecting upper portion of the insert therein, the common bottom of the body portion and of the rod supporting extensions thereon will be flush with and exposed at the bottom of such slab for knockout removal of the insert through such slab by a hammer blow on the top of the projecting upper part of the insert after such slab has been tilted to upright condition by hoisting means inserted in the hole in said body portion.

2. An arrangement according to claim 1 wherein a pair of supports extend laterally from the lower end of the body portion at right angles to said rod supports, the bottoms of said supports being flat and co-extensive with the bottom of the body portion, and all laterally facing surfaces of said supports also converging upwardly.

References Cited in the file of this patent UNITED STATES PATENTS 1,135,065 Shipley Apr. 13, 1915 1,663,974 Cook Mar. 27, 1928 2,772,560 Neptune Dec. 4, 1956 

